Eye gaze tracking has many potential attractive applications in human-computer interaction, virtual reality, eye disease diagnosis, and so forth. For example, it can help the disabled people to control the computer effectively. Also, it can make an ordinary user control the mouse pointer with their eyes so that the user can speed up the selection of focus point in a game like Fruit Ninja. Moreover, the integration of user's gaze and face information can improve the security of the existing access control systems. Recently, eye gaze has also been widely used by cognitive scientists to study human beings' cognition, memory, and so on. Along this line, eye gaze tracking is closely related with the detection of visual saliency, which reveals a person's focus of attention.